[limekyle19]

I have a powermax 85 and 220 single phase power. what size breaker do I want to use? 60amp 100amp? The owners manual isn't very clear on what to use.

[limekyle19]

Really find it hard to believe that nobody else has a powermax 85, 45 views and not one response?

[plasmamatt]

We have a Thermal Dynamics A80 and our electrician used a 100 amp breaker.

[will_eng]

I have a powermax 1250 which is an 80A output. I am using a 60 amp 220V single phase breaker. I also ran 6 awg wire. I think this info is listed in the manual for your machine.

[ej4]

If you go to the Hypertherm website for the PM85 and look at the Specs tab, it shows the following input current for single phase:

200/208/240/480 V, 1-PH, 70/68/58/29 A

So I'd go with those numbers depending on what your input voltage is. Your breaker and wiring needs to be sufficient to support the current listed.

Is there something else you're looking for?

[jimcolt]

The attached chart for suggested fuse sizes in in the operators manual that is shipped with every Powermax unit....it is in the section for Power Supply Setup.

I have a powermax 85 and 220 single phase power. what size breaker do I want to use? 60amp 100amp? The owners manual isn't very clear on what to use.

[limekyle19]

Alright then what is Input during arc stretch mean? and also slow blow fuse mean?

[ej4]

The attached chart for suggested fuse sizes in in the operators manual that is shipped with every Powermax unit....it is in the section for Power Supply Setup.

ah - rtfm? lol thanks for the link, Jim!

I was also looking at the 65 and 85, but not sure I could do the 100A....so may have to go w/ the 65.

[jimcolt]

The amount of power produced by a plasma arc is determined by two things....the amperage setting, and the arc voltage. Arc voltage is proportional to arc length.....if you cut thicker material or have a high torch to work distance...the voltage output is higher.

So....say you have the amperage set at 85 amps and you cut 1/2" steel....and measured the arc voltage (put a voltmeter between the plate being cut and the torch electrode).....you would see a voltage somewhere around 110 volts DC. Multiply 85 (amps) x 110 (volts) and that comes to 9,350 Watts.....or 9.3 kW (killowatts).

At the same 85 amps....cut a piece of 1"....measure the arc voltage, you will see (I am guessing a bit here) approximately 130 volts DC....85 x 130 = 11,050 watts (11 kW).

So...even though the cutting amps stayed the same....the power supply has to produce more power to cut thicker materials....as the arc is longer (stretched). If it is making more power for the torch....it will draw more power from your input power source.

Hypertherm provides an amperage input number for "Maximum arc Stretch" for those applications where you may be running at full amperage output.....and a really long arc......such as the gouging process. Sometimes with hand cutting you have some tight spots to get into and you cannot get real close to what your cutting...this will stretch the arc....and require more power as well. For mechanized cutting on a cnc machine.....the only arc stretch is normally based on the thickness of the plate being cut....so you can base your input power circuit a little smaller...especially if 90% of your cutting is way thinner than the maximum severance thickness rating for the plasma.

I have been running a Powermax85 in my home shop for over a year on a 60 amp, 240 volt circuit. I do not do big production runs on anything over 5/8" thickness.....although I occasionally cut up to 1" plate (I have never tripped the 60 amp breaker). If you are heavily into thick plate cutting...you need a 100 amp, 240 volt input circuit. If you are cutting thinner materials as I do....you can get away with a smaller circuit. My 60 amp circuit is marginally small.....but the worst that can happen (as long as the circuit conductor sizes are correct for the breaker size) is that the breaker will trip when I am cutting heavy material.

Hopefully the above long winded explanation helps with the question about "Arc Stretch"

The term "Slow Blow" when referring to electrical circuits....means a fuse or a circuit breaker that does not instantly blow or trip when its current rating (Amps) is exceeded. This is to protect from the instantaneous spikes of amperage when cutting off the end of a plate (arc stretch) or crossing a kerf....which normally can occur with plasma cutting. Any electrician will understand the term.


Jim Colt Hypertherm

Alright then what is Input during arc stretch mean? and also slow blow fuse mean?

[limekyle19]

Thanks Jim for the detailed explanation on this! This has answered all my questions and I now know what size wire and breaker I need to get!